1. Field of the Invention
The present invention relates to a link system for photonic cross connect and transmission apparatus, and in particular, to a link system for photonic cross connect and transmission apparatus which enables highly reliable and highly efficient operation of an optical network.
2. Description of the Related Art
Lines in GMPLS optical networks using photonic cross connect (PXC) include a line of an in-use system being currently used in which optical signal from client apparatus is inserted and a line of a backup system maintained for backup without optical signal inserted therein (except for 1+1 protection).
In a transmission apparatus such as a wavelength division multiplexed apparatus (hereinafter, referred to as WDM), considering detection of an error between a PXC and a WDM depending on whether light is inputted from the PXC, light is not inputted from the PXC into the WDM that forms the backup system, so that it cannot be distinguished whether light is not inputted due to an error between the PXC and WDM or light is not inputted due to the backup system between the PXC and WDM. Therefore, it is not possible to detect an error between the PXC and WDM by detecting whether light is inputted from the PXC into the WDM. To avoid this problem, conventionally, error alarms between PXC and WDM have been all masked and errors between the PXC and WDM have been ignored.
However, in the above conventional method, error alarms between the PXC and WDM are all masked and errors between the PXC and WDM are all ignored, so that an operator cannot determine errors between the PXC and WDM and cannot quickly cope with errors.